Page 32 - Curriculum Visions Dynamic Book. To close the book, close the tab.

Pollution
Any addition of a significant amount of material into the air that disrupts the natural environment. Atmospheric pollution is mainly in the form of acidic gases such as sulphur dioxide (which cause acid rain), dust particles (which cause haze) and carbon dioxide (which causes the greenhouse effect).
(See also: Smog.)
 Pollution – Los Angeles is among many places that suffer from photochemical smog in summer.
Polar climate Polar climate
Very cold climates of the high latitudes, where the average temperatures in the warmest month do not rise above 10°C.
Polar front
The line that separates cold
polar air from tropical air in
the mid-latitudes. Depressions form along this front and then move eastwards.
Polar jet stream
A tunnel of very fast-moving air
that encircles the Earth high in the atmosphere, close to the polewards limit of the mid-latitudes. It forms into great waves as it moves.
These waves influence where depressions and anticyclones will appear in the mid-latitudes. In general, anticyclones emerge on parts of the waves that turn towards the equator, while the parts of the wave that turn towards the pole are the sites of strings of depressions.
Polewards
Moving in the direction of (or towards) the North or South Pole.
Precipitation
Liquid and solid water that falls or condenses (see: Condensation) from the air – rain, snow, hail, dew and so on.
Pressure
The weight of the atmosphere
on a given area. The terms high pressure and low pressure refer
to the air pressure in the part of the atmosphere near the ground. A region of high pressure is formed where air currents cause air to sink over a region of the Earth, thus adding to the weight of the air. A region of low pressure is an area where air is rising, counteracting the normal weight of the air.
Pressure systems
The lows (low pressure systems) and highs (high pressure systems) in the atmosphere.
Prevailing westerly winds
Winds that blow across the mid-latitudes from west to east. They contain depressions and anticyclones and signal changeable
weather. Also called westerlies/ westerly winds.
R Radiation
The transfer of heat through
space and the atmosphere by the vibration of atoms. The weather is entirely driven by the heat energy that is radiated from the Sun.
Heat is lost from the atmosphere and from the surface of the Earth by radiation. This is especially noticeable at night, when heat is lost by radiation if the sky is cloudless.
Clouds can reflect (bounce back) radiation. That is why heat is kept in on a cloudy night and why a cloudy day is colder than a sunny day.
Radiation fog
A type of fog caused by the ground cooling, usually overnight. Radiation fog is seen over rivers and in the bottoms of valleys, where the cold air gathers over moist surfaces.
Radiosonde
A set of instruments that are carried aloft by a helium balloon so that the conditions of the atmosphere can be measured. The measurements are transmitted electronically, using a small radio.
The information is sent back to a ground receiving station.
The most common observations made by radiosonde are temperature, humidity and pressure.
Radiosondes are an important aid to weather forecasting.
32